Reid Epstein and I look at what Rick Perry was going for with his very personal hit on Mitt Romney on immigration:

Rick Perry went into Tuesday night’s debate looking to rattle Mitt Romney — and it worked.

Perry’s been under fire for his own immigration record, and resurrecting the 2007 report that Romney had hired illegal workers helped him blunt the advantage Romney had been able to get on the issue as Perry looks to recover from his collapse in the polls.

Plus, according to a Perry source, there was an added bonus: by going after Romney personally — the accusation has to do with Romney’s own house — they saw the potential to make Romney react the hardest.

And despite the headlines at the time, the issue didn’t get the attention Perry’s campaign believes it could have when it surfaced in Romney’s first run for president four years ago, and gives Perry a new opening into coming at Romney as a flip-flopper.

“This is the start of Romney vs. Romney. We’ll have him debating himself before this is over,” said one senior Perry adviser, explaining the strategy.

For now, Perry's main goal is to try to raise issues for voters about whether they can trust Romney. If he can accomplish that, he can help himself get a new look from voters.

But one thing stuck out from Perry's response - he declined to use Rudy Giuliani's signature and memorable line on the lawn workers, "sanctuary mansion."